The joyless nature of Irredeemable left me cold. I got 4 issues in and really didn't care anymore. I've never even heard of Incorruptible.
I haven't read Incorruptible yet; I'm waiting for the trade (or possibly, the Longbox edition).But I like Irredeemable an awful lot (though I've only read the first trade of that, too...)
I'm really looking forward to Incorruptible, though, because the redemption storyline sounds like something I'd really enjoy.